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WiFi standards explained: what you should know about the new 802.11 ad, ah & af standards

WiFi is a crucial technology found inside our smartphones that we all use every day, but if you’ve ever stared a little longer at a spec sheet or your home network router you will probably have noticed that there are a few different number and letter combinations tagged on the end. These different designations define some quite different properties of the overarching WiFi standard, so here’s an explainer to break down the differences.

A brief history of standards

First up, let’s deal with that weird looking 802 number. This naming system is actually used by a number of networking standards that you will probably be familiar. Ethernet networks begin with 802.3, Bluetooth has an 802.15 prefix, and WiFi is tagged with 802.11. All the different WiFi varieties will begin with this 802.11 number, followed by a letter or two which, from a consumer point of view, is useful for identifying other properties, such as the maximum speed and range of the particular device.

To help ensure compatibility with different pieces of hardware and networks, you’ll often find that products support multiple, if not all of the standards at the same time. You may have seen a listing like Wi-Fi 802.11 a/b/g/n/ac on the spec sheet for many smartphones, which covers all of the oldest and most common modern standards.

Much of the renaming has simply come about to help define incremental improvements to the standard, mostly in terms of speed increases. More recently, WiFi has been splitting into some quite different branches, but we’ll get to those in a minute. Here’s a breakdown of how the most commonly used versions compare:

802.11 (legacy)

802.11a

802.11b

802.11g

802.11n

802.11ac

Max Speed

1.2 Mbit/s

54 Mbit/s

11 Mbit/s

54 Mbit/s

150 Mbit/s

800 Mbit/s

MIMO

no

no

no

no

up to 4

up to 8

Frequency

2.4 GHz

5.8 GHz

2.4 GHz

2.4 GHz

2.4 & 5 GHz

5 GHz

Year

1997

1999

1999

2003

2009

2013

Following the initial launch of the WiFi standard, 802.11b became the most commonly adopted in consumer devices, partly due to its lower cost. This was replaced by the much faster 802.11g three years later, which retained backwards compatibility to maintain support with existing hardware, but left the revision with some of the old drawbacks.

While the move from the original standard through to 802.11g was mostly about speed improvements, 802.11n introduced the first optional use of the 5GHz band, a frequency that is much less cluttered. The n revision also introduced the first use of MIMO antennas for higher parallel throughput. Speeds can theoretically reach up to 450 Mbit/s, depending on the number of antenna connections.

The last major revision to the main WiFi standard was 802.11ac, which was designed to dramatically increase the speed of data transfers. This is the first standard on the way to “Gigabit WiFi” where speeds can reach 1 Gbit/s, by far the fastest WiFi version to date. 802.11ac also runs solely on the less cluttered 5 GHz band and this higher frequency and modulation rate allows for a higher speed, at the expense of range compared with 2.4 GHz 802.11n or g.

The future of WiFi

There are new WiFi technologies just hitting the market and more on the way in the next few years too. These mark some quite different approaches to WiFi that could enable some entirely new device classes. One of the most recent to crop up is 802.11ad, which just appeared in the new Le Max Pro smartphone, powered by a Qualcomm chip.

802.11ad takes a very different approach to existing WiFi technology, aiming for a massive boost in speed at the expense of range. This version opts for a very high 60 GHz transmission frequency that enables data speeds to reach around 7 Gbit/s, which is fast enough to potentially use for wireless hard drives. However, this comes with a major trade-off to range, as the frequency cannot penetrate walls and requires a direct line of sight to the router.

802.11ad is suitable for fast data transfers within a single room, but not for a complete home or office network. This does however have promise in living room situations, where users may want to transfer a huge 4K movie file from a device to a TV. However, it is also currently quite an expensive technology to implement.

Of course, there are new revisions on the way for longer forms of WiFi communication too. In fact, the recently announced 802.11ah standard, also known as WiFi HaLow, is designed to reach up to reach 1 kilometer (3,300 ft), providing that certain conditions are met.

To achieve greater coverage, 802.11ah is transmitted at just 900 MHz, a much lower frequency than the existing 2.4 GHz and 5 GHz WiFi technologies. The trade-off is that speeds greatly decrease the longer the distance from the transmitter and devices will only be able to transmit data at speeds between 150 Kbit/s and 18 Mbit/s, making it slower than most existing home networks. However, this is quite well suited to low power devices that only require the transmission of short bursts of data, such as Internet of Things devices.

The final specifications for 802.11ah aren’t expected until March 2016, after which WiFi chip manufacturers can begin designing and producing hardware components for use in future products. The first HaLow certified devices will ship from 2018, according to WiFi Alliance.

One last interesting development in the WiFi space is talk about 802.11af networking. This has also been dubbed White-Fi or Super WiFi and uses television spectrum frequencies between 54 MHz and 790 MHz, potentially making this the longest range WiFi technology yet, with miles of coverage.

This would again be helpful for long distance IoT communication and could also be used in business or industrial applications that require long range communication. Speeds could be acceptable over these distances because of the lack of interference, however these frequencies will be unavailable for WiFi in some regions, limiting the potential consumer applications.

Wrap Up

WiFi is faster than ever these days and has clearly undergone a major transformation since its conception almost two decades ago. Importantly, WiFi networking is keeping up with new ideas, such as the Internet of Things and the demand for higher resolution content. However, as a result we may have an even bigger list of spin off of standards to keep an eye on in the future.

Lead Technical Writer at Android Authority, covering the latest trends in consumer electronics and hardware. In his spare moments, you'll probably find him tinkering with audio electronics and programming.